I'm here again!!

This time it seems a complete mystery!
The lovely Jason who looked at the rear
wheel ( it had lost 3 pounds in 3 days )
said he check the rim seal, valve and tyre
for any sharp object! He couldn't find
anything suggests I check pressure on
Friday and if it had lost anything at all he
will remove tyre and check inside, he is
baffled, so am I . Well it's a hassle but
best to be save and sure.