I've noticed quite a few packets of durum wheat semolina (supermarket own-brand dried pasta) has this warning. This applies to macaroni and spaghetti etc. but similar products from other supermarkets don't have this.
I've also seen it on raw cubed beef and sausages from other supermarkets in the UK.
While I can understand this warning on meat products, and would expect such a warning on storing/reheating rice (but haven't seen that many), it would seem more appropriate to give the appropriate storage/reheating advice than just a blanket, terse "Do not reheat". If taken literally, this would be goodbye to special fried rice, reheated casserole or lasagna.
Provided the dish was properly cooked, stored and reheated, I cannot think of any food safety risk by doing so (especially in the case of pasta). Is this just legal overkill, food presentation advice or marketing jargon to sell more product? Or am I missing some critical food safety factor here?