Are Linear Gradient's suppose to be automaticly deleted when the use count hits '0'?

The reason I'm asking is I was playing around with a file of mine which had separate gradients on each the stroke and fill. If I had selected one or the other, then clicked on gradient that was used on the other part of the item, Inkscape deleted instantly the one that was now no longer in use (since it's count hit 0) from both the selectable gradients and even the file. (I could hit Undo to get it back, but if I had saved the file and closed Inkscape thinking it was still in the file Defs, that could be considered data loss even though there is no crash.)

So, is this what Inkscape is suppose to do, or might this be a bug (and I'll file a proper bug report later today when a example file if it is a bug)?

Inkscape 0.91 r13725 x64 (MSI)
Windows 7 SP1 x64