I'm never had an issue with a bedded, fiberglass stock.
Mostly haven't with wood, bedded stocks. Have with unbedded wood stocks.
Why so many follow the 'If it shoots good, don't worry about bedding it' mantra is beyond me.
Understandable, but I'm one that doesn't worry about bedding if a rifle shoots well, preferring to leave well enough or better - and often much better - alone. Mostly I've only found re-zeroing to be necessary when changing loads or ammo batches.
That said, I do free-float my wooden-stocked rifles and helped my buddy do his when he first got it back in 1999. His Ruger MKII 7mm RM goes year to year with 160g Grand Slams without needing adjustment, using ammo he built several years ago. When we checked it a month ago it was still on from last year, +2" at 100 and pretty much matching calculated drops out to 600. Last week I fired it for the first time in years when I had a user-induced ammo malfunction with my .338WM. Took down a 6x5 bull at 411 yards, quartering away, with a shot placed exactly where I wanted it - about 6" behind the front leg, centered vertically and angling to a point just ahead of the far leg.
His rifle isn't bedded and my guess is history will repeat again and that rifle will still be zeroed the next time we get it to the range. None of my Rugers are bedded either and all shoot well enough that I don't mess with them.