My pHep5 does that too, I just assumed the stuff was a strongish buffer so I always make sure to rinse it well and wipe it dry before even putting it in my distilled water before measurement. I always stick the clean/dry probe in distilled water and then dry it again before putting it in any calibration solution or sample (I'm trying to reduce any buffers from carrying over to anything else).
FWIW AJ, I have a couple of ~250 gal heated caustic tanks at work and that stuff is kind of a ***** to 'seal'. It also wants to crystallize (and we use the liquid stuff). It creeps into pump seals and threaded areas/etc. but a combination of t-tape and pipe dope seals threads (like the screw-plug heaters) pretty well. Then we paint the aluminum pump motor face with Super Koropon to protect it when it inevitably creeps past the pump seal.