It means there is something out of date. Refer to the copy/paste below from the UG bbsnotes page:
"The [!] in front of the displayed part name means that either the WAVE data, WAVE Link, or mating conditions are out of date. By using the Assembly Navigation Tool you can determine which component part file need to be updated. When a part becomes out of date, the symbols (!) appear at the bottom of the graphics window.
Please note, that there is an exception to having something out of date which really isn't. This is a note from UG's development Programmers: When delay interpart updates is turned ON and a user goes thru "Playback" it's considered
"out of date" and can show the ! (in front of displayed part). This is because it has tried to update the source object, but was not allowed to because the delay was turned on, so from ug's point of view it is out of date.
So, to sum up, a body can sometimes never really out of date, but running playback with delay turned on cause ug/parts to think they are out of date, which can cause
confusion. This is "as designed" by UG development."
Tim Flater
Senior Designer
Enkei America, Inc.