7 year old Lakeland Terrier Female

She suddenly a few weeks ago began to get nervous each day when wife
gets home from work mid afternoon, despite being closest to my wife.
Dog begins to shiver and pant, jumps at noises, soon after wife comes
through door. She still wants to sit in wife's lap at these times. Dog
is fine up to this point every day. She eventually calms down after
3-4 hours. No other pets in house, just wife and myself.

Any thoughts?