Breathing funny when purring

[labcat]

My cat is Bell, she is a very loving sweet girl, about a year old. No particular breed, grey DMH with faint tabby stripes.

Our vet diagnosed her with Feline Herpes as the cause to her mucus accumulation in her eyes and nose (boogers). He listened to her lungs and heard no abnormalities, she is in otherwise good health as far as I know, and is currently healthy otherwise, as far as I know.

What has me a bit concerned is that when she purrs her stomach rises and falls more than when she is breathing relaxed. Its is almost rhythmic and you can hear a difference in the sound of the purr when she is breathing in as opposed to when she is breathing out. Similar to this cat: http://www.youtube.com/watch?v=bvu6aLW0rQA . Occasionally she will also have a little cough or clear her throat when she is purring too, and last night (unless I dreamed it) she started to sound a bit extra funny and needed to open her mouth a swallow a couple times; again only while purring.
If that happens again, it will mean a call to the vet.

Is this something that is caused by the Herpes infection?
Could it be something else like asthma? [she has done the about to have a hariball-and doesn't thing a couple times, but she is on hairball control food because she did have hairballs before]

Any help would be appreciated.
Thank you
Steph and Bell