"So, in a round about way, Coinbase invested my money for 4 months and returned it to me with an incredible return. "Roundabout you say? ;) lol Indeed Coinbase o some other entity "borrowed" your bitcoin without your permission, without promise of return, and your BTC put it into your account when "they "were through with it. I wonder , mildly curious, what your .03 BTC was being used for. I wonder if this happens "randomly" and at will with some statistically significant frequency

If Coinbase or anyone else for that matter wants to borrow BTC, they can do so on BitConnect and pay a fee for the priveledge. Your BTC was borrowed, interest free, for 4 months, with neither your blessings nor permission. Sounds a bit shady to me. Maybe somebody wrote a script that targets, culls, re-routes and then returns BTC intact at some later date. The value of the BTC depends on the market. Whether you spend, exchange, or hoard your BTC should your decision not some benevolent thief's decision.