Port scanning is a reconnaisance technique used to gain information to be used to later gain unauthorised access......where I honestly think by your post that you are more curious than malicious, a 'target' company may not quite see it the same. Should you do as nebulus mentioned and screw up and cause a DoS or probe a bit deeper out of curiosity. You may be facing prosecution, many more companies have security policies that create a basis for legal action against network intrusion. Those banners about unauthorised use and prosecution are there to create such a basis and not just scarecrows.
Best thing would be to leave it alone or just play on your own network if you have one. "I pressed the wrong key your honour" ain't much of a defense