if it were mine, i would replace the caliper hoses. it has been known they can collapse internally, acting like a one way valve. the hose problem affects other makes and models as well, so not anything really new.
while it is apart, you may also consider replacing the master cylinder, as it may be acting up.
that should take care of your problem.
i have seen problems crop up on low mileage vehicles of all kinds, just from not driving them.
just my experience in life. your mileage will vary.