Do you still have your old bulbs?
I would recommend swapping abck to them. 3 months is about the right time for the wrong spectrum of light to really make an impact. It's only a theory and it's a loose one at that.
however, in my experience, Flour, halides, and any light that is trying to give off a designated spectrum of light is subject to flaws. I own a company that specializes in concert lighting and audio... we see alot of lamps and there is a given percentage of failure and fatigue. Unfortunately manufacturers don't always hit 100%.
I once got home 4 x 65 PCs all Actinic... fire them up and a spectrometer showed each had ALOT of variables... but put out spikes at the right level.
Just my 2 cents.
If you do check into this direction... don't disregard other possibilities. This is only a theory.