Question about return of taste

I've just read a whole bunch of posts here and people generally say taste returns slowly but progressively: eg, first salty, then bitter, then sweet, etc.

My husband is only 4 months out from radiation for tongue cancer, so we're not expecting big things taste-wise, but he's finding it comes and goes. For example, for a few days he can taste the mushrooms in a sauce, the next week the sauce has no flavor at all. It feels like a month ago he was tasting quite well, and today he tastes nothing.

This is normal, right -- it can come and go until it's back for good? Or should we check this out with the team?