Broker Shore Capital may downgrade profit forecasts for pub group JD Wetherspoon, but said any share weakness could be a buying opportunity.Wetherspoon on Wednesday reported a good February and March, but said sales slowed in the last few weeks.Shore, which has a 'hold' recommendation on the shares, said it could reduce 2014 annual pre-tax profit expectations of £79.6m by up to £2m, but pointed to pub openings as a potential source of future earnings.Analyst Greg Johnson said: "We continue to struggle squaring Wetherspoon's like-for-like sale growth and operating margin with cost rises running materially ahead of inflation, implying the group is investing ahead of future growth," he said."With the group also having bought back about £9m of shares in the period, we would see any weakness today as a buying opportunity."At 11:04 in London, shares in Wetherspoon had fallen 18.5p or 2.2% to 833.5p.PW