Well, the new leaves may get zapped but at least the plant will n-o-t be killed.

I had that happen once and the leaves came back but frankly, it was such a pain that I decided that, the next time, I would pay attention to my avge date of last frost and add a week or two.

Yes, your plant will recover if the buds get zapped by a frost but those may be the buds that will ultimately produce flowers. I wouldn't chance it. Resist the urge to uncover before your last frost date. And be prepared to cover with blankets if there is a late freeze.

Keep looking at your 10-day forecast. If forecast lows don't read below about 36 I would go ahead and get a jump on cleaning up your beds. Even in Pittsburgh I'd consider myself safe at this point, or at least because I have a stack of old linens I can use as throws on the chance temps are forecast to go below 28-ish degrees for 4-5 hours (my "golden rule" of hydrangea damage). There have been many nights of 30-31 that resulted in no damage.

My beds are all clean and trimmed and ready to go. Having trimmed off the topmost dead stuff has already encouraged buds and shoots to start moving. The real fight is not frost but deer (and rabbits) that are trying to literally eat things as they are popping out of the ground! I do not believe in animal cruelty but I'm not afraid to unload a few mags of BB's from my air pistols, at least to scare them off.

I would agree that light spring frosts are of little concern. We can get our share of them here and my hydrangeas - never protected - sail through them with no leaf damage and no loss of flower buds. A hard freeze is another matter altogether and I would follow Springwood's recommendations if something like that is forecast.