I am not worried at all by the outing but everything that happened does kind of square with his scouting report (especially the impressions that Keith Law reported on a few weeks ago). Hitters can time his fastball a little too much because his secondary pitches are weaker. This means that he might give up more hits the 2nd or 3rd time through the lineup, especially against more advanced hitters. They may not do much against a 98 mph fastball with some life, but they can hit it.
I was a little concerned he threw a record number of pitches (84). No reason to break records in his first high A outing. Would have held him to 65-70 because I would not want him overthrowing. Next season can be the year to start getting him closer to 100 pitches.
I do think he could still move relatively quickly if his secondary pitches improve, especially his curve or slider. It just depends if that is next year or 3 years from now. I would not be concerned with whether he starts at Reading next year or not, though I will say he is the type of pitcher that if he gets to AA the Phillies might decide he is ready for the majors. I don't expect it next year, but it is at least possible.