Potterton Suprima, flashing amber light?

I had the dreaded PCB lockout issue a couple of years back, and had the PCB replaced. Bolier now works perfectly, except on two occasions recently the boiler seems to have reverted to a flashing amber light, does not come on, then eventually (after an hour or so) comes on and is working fine again. Is this normal? I have been caning it a bit recently what with the cold weather, do these things sometimes generally need a "rest/cool-down" period? Or is this an indication that this problem could get worse?