I've rarely felt it, although I have met this beast and it's not nice.
I've played/DMed through a total of 17 levels, up to level 8.
Thinking about it, I haven't played any games where it's been a grind and boring. I've played long and tactically difficult battles. I've rarely been bored because of just using at wills.
I've played fights which were so tough that they wern't much fun- vs a brass warden in thunderspire, for example, and vs dragonshields way back at first level (they just shift away, so you rarely get to use a power on them, only charge). Also vs a young black dragon at 3rd level. but we died then, so that might have been why.
I've also played whole-evening encounters which have been very tough, but awesome, such as the end of KOTS, where we were out of powers and healing and I spent a long time fighting very bloodied, including a final 5 rounds at 3 HP (that was a conflict between character and sense, and character won- being a paladin can hurt!).
I think that a party without striking power is more at risk of grinding. Monsters that can make a grind tend to have very high defences, or high HP compared to damage output, or negate the players abilities, or have unavoidable damage resistance.