LONDON (Reuters) - Oil prices on Tuesday surrendered some gains made over the previous days as investors reconsidered the likelihood of immediate supply disruptions in the Middle East after the United States killed a top Iranian military commander. Brent crude was down 41 cents or 0.6% at $68.50 (52.06 pounds) a barrel at 1122 GMT, while U.S. West Texas Intermediate (WTI) crude was at $62.95, down 32 cents or 0.5%. Prices surged during the previous two sessions, with Brent reaching its..