UTM9 Update to 9.703-3 causes mail problem?

Question

At 14:13 yesterday I updated to 9.703-3. 
 I have just done a routine Mail Manager check and there is a build-up in the SMTP Spool, starting at 14:14 yesterday, of mail with 'AV Scan pending' 
 Is this a strange coincidence? 
 Even more strange coincidence, I saw there was an email problem with UTM exactly 1 year ago.

PeterRiggs · Accepted Answer

Thanks for the suggestion. 
 I did a reboot and just returned to find that email is now coming through. 
 I shall mark this as an answer in case it helps others.