Dipstick testing is highly sensitive and picks up tiny amounts of protein (and blood) that isn’t necessarily of any concern.
A significant proportion of well people will have one or 2 pluses of protein on dip testing at any one time. More common with intercurrent illness.
Can happen with urine infection. Can happen with exercise.
Large amounts of protein loss can indicate nephrotic syndrome. PCR (or ACR) would typically be above 200.
Rarely PCR can be extremely high, but turns out not to be albumin but Tam Horsfall protein – can be ignored!