psa: check your bed probe mounting occasionally

I've been having weird first layer issues for months. My z offset seemed all over the place and I found myself manually adjusting each print. Had no clue what the issue was until I noticed my bltouch wasn't perfectly straight. Turns out the mounting screws had loosened slightly leaving ~1/2mm play in its location compared to the nozzle. Tightened then up and printed my first absolutely perfect first layer in months.