Yes, genuinely — and this is one of the clearest, most direct causes of a beer coming out darker than its calculated SRM predicts, because boil-driven darkening isn't part of the Morey equation's inputs at all.
Why the calculator doesn't see this coming
The SRM calculator computes colour purely from grain weight and Lovibond rating — a grain bill computing to roughly 7.7 SRM (4.3 kg pale malt at 3°L plus 0.3 kg crystal at 40°L, in 19 L) renders that number regardless of whether that batch is boiled for 45 minutes or 120. In reality, a longer, more vigorous boil produces measurably more colour through two real chemical processes the formula has no way to account for.
The two mechanisms actually responsible
Maillard browning — the same reaction that browns bread crust and seared meat — occurs between sugars and amino acids under heat, and accelerates with both boil time and boil temperature. Caramelisation of wort sugars adds further colour independently, also accelerating with time and heat. Both effects compound gradually rather than kicking in at some threshold, so a 90-minute boil produces visibly more of this effect than a 60-minute boil on an identical grain bill, and a hard, vigorous boil produces more than a gentle simmer at the same duration.
How much this actually matters in practice
For a normal 60-75 minute boil at a standard rolling boil, this effect is real but modest — usually not enough to move a beer between colour "bands" on its own. It becomes much more noticeable on unusually long boils (some big, high-gravity beers are boiled 90-120 minutes specifically to concentrate and darken the wort as part of the intended character) or on a scorched boil, where localized overheating at the kettle's heat source produces disproportionate, uneven darkening well beyond what boil time alone would predict.
What this means for recipe planning
If you're deliberately planning a longer boil — common for high-gravity beers needing extra concentration, or styles that traditionally use an extended boil for flavour development — expect the finished beer to read somewhat darker than the SRM calculator's grain-bill-only prediction, and don't chase that gap by removing dark specialty malt from the recipe to "correct" a number the formula was never going to match exactly in the first place. See why is my beer darker than expected for the fuller list of process factors, of which boil length and intensity are usually the biggest single contributor once mash pH and ingredient accuracy have been ruled out.