No, I dont think it is normal. The PCC i got myself does not even mention since how long, it just says as of this date, there is no issues. so please go back and get a correct PCC.
well , as far as i know this is normal ,, because police certificate is issued if you stay in particular country for more than 6 months,
so they have to indicate the date of enterence. dont worry pal you dont need to correctit , i hope