[NTG-context] \everymath problem

Hi, I use luatex 0.43 with yesterday's beta. Running \everymath = {\displaystyle} \starttext ${a\over b}$ \stoptext results in ! Use of \dospecialabout doesn't match its definition. l.4 ${a\over b }$ Plain format under luatex has no problem here. If I change \over to \times it runs with fonts changed to roman (i.e, not math italics). Thank you. Eythan