Turntable sibilance

First of two queries by me today....

I have a VPI Classic 3 with Soundsmith Zephyr (original) cartridge and MMMicroOne speakers (just upgraded significantly (I hope!) to Sonus Faber Olympica III’s, which I received today but haven’t yet plugged in). While listening last night, I noticed some audible sibilance (hissy S’es) on vocals. Never noticed that before. If it had been occurring before, I probably would have noticed: turns out I’m fairly sensitive to sibilance, I guess...

I noticed it when listening to multiple "reference" records, all of which are well cared for and good pressings. It’s still minor, but is noticeable. It is not limited to the inner grooves.

From reviewing various past threads here, I gather there could be several culprits: a worn stylus, or incorrect VTF or VTA. As to the latter two: Can those "drift" over time on a VPI Classic 3? I ask because if the problem was the VTF or VTA, the sibilance would not have appeared spontaneously last night, but would have been there from setup. Once I initially set VTF and VTF, I have not changed them and the screws are locked down tight. I do not have any anti-skate on, per VPI’s recommendation (I realize that many disagree with that recommendation, but it’s been working fine for me til now; in addition, as noted above, the sibilance is not limited to the inner grooves.

As to the former: I bought the cartridge used here on Audiogon, but it had had a "complete rebuild" by Soundsmith. I bought it about 18 months ago, but have only put about 1000 hours on it. (If I’m lucky, I get to listen about an hour or two per day. Taking 2 hours daily 7 days a week for 18 months = 1095 hours at the absolute most, and realistically, it’s probably less than that since I don’t always get two hours of listening every single day). I’ve read that a good cartridge should go about 2000 hours before any noticeable wear.

I realize that the easy solution is to dismount the cartridge and send it to Soundsmith to check. Before doing so, I will re-check VTA and VTF. Any other advice is appreciated. I’d hate to have the cartridge out of service for several weeks, having just gotten new speakers.

Thanks!