For the record, I'm not claiming to know the cause or reason for the behavior. What I did was give a prescription; Irrespective of what the problem or issue is, increased exercise would probably be a healthy way to decrease anxiety (whether it's seasonal, mood-related, etc.).
If a dog has anxiety (about anything for any reason) then their need for exercise goes up; this is required to healthily decrease stress. Whatever the cause for the anxiety, a simple and (usually) effective way to deal with it, is through increasing exercise time and/or mental enrichment time. This also holds true for dogs with pent-up energy/restlessness/boredom/reactivity/etc.
The posts directed at me were deleted, so I can't reply to them.
All the best.