Slight foamy urine. Spot urine test-protein 5mg/dl, creatinine 37mg/dl, albumin 2 mg/litre. Is it normal or proteinuria?

Proteinuria. We generally calculate the urine protein to creatinine ratio and as long as the ratio is below 300 mg/g it is considered not significant (yours is only 135mg/g) so your proteinuria is not significant. But the Albumin level you mentioned, is it serum (blood) Albumin level? If yes, it is very low and unlikely! Please verify your Albumin level and it's source (blood or urine) . .
Not a concern. Trace / mild protinuria, up to 300 mg/day or 300 mg/Liter, is basically never a concern, except as a marker for progession to renal disease in a known diabetic. You can get it from exercising or the stress of mild illness, and many people get it just from standing up. If your physician isn't concerned, don't be either.