In Czech glass you often find polished rims, as this is an efficient way of finishing a piece. The process if somethings called "blown from the top" - but not everyone likes that term. It means that a piece is blown in a mould and cracked off - the final operation is then polishing the top smooth. The alternative is to hot finish the rim with tongs. It is more elegant, but requires an additional operation, namely a pontil rod, as well as cracking off the pontil rod and finishing the mark.
Both methods have been used by all glass makers everywhere. You do not spend more work on a piece than necessary. And it is not an indication of age, only quality. Incidentally, if a piece has a polished rim AND a pontil mark, it may be reworked, as it makes no technical sense.