B737 CREW HAD ALTDEV IN ZHU CLASS A AIRSPACE.

Narrative

CRUISING AT FL330; FO REQUESTED FLT PLANNED ALT OF FL350. ZHU ADVISED US OF XING TFC AT FL350; AND 'EXPECT FL350' ONCE CLR OF TFC. FO ACKNOWLEDGED. CAPT MISUNDERSTOOD RADIO XMISSION AND INITIATED CLB TO FL350. AT APPROX FL340; ZHU QUERIED US ABOUT OUR ALT. CAPT DISCONNECTED THE AUTOPLT AND EXPEDITED A DSCNT TO FL330. FO WAS UNAWARE OF CAPT'S INITIATION OF CLB. HUMAN PERFORMANCE CONSIDERATIONS: 1) COCKPIT CRM AND PROCS BREAKDOWN. 2) XING TFC HELD FO'S ATTN AS A VISUAL WAS OBTAINED. 3) CONFIRMATION OF NEW ALT OF FL350 WAS NOT OBTAINED BY THE CAPT (PROC). ATC WOULD HAVE BEEN QUERIED AND THIS DEV WOULD NOT HAVE OCCURRED. SUPPLEMENTAL INFO FROM ACN 485750: CRUISING AT FL330. FO REQUESTED FLT PLAN ALT OF FL350 FROM ATC (HOUSTON 132.7) FO HEARD AND READ BACK 'EXPECT FL350' AND TFC CALL. CAPT UNDERSTOOD CLRNC AND READBACK WAS TO FL350. FO WAS ACKNOWLEDGING/POINTING OUR TFC AT '2 O'CLOCK POS' AS CAPT DIALED FL350 IN ALT WINDOW. ATC QUESTIONED ALT CLBING THROUGH APPROX FL338. AUTOPLT DISCONNECTED AND ACFT DSNDED TO FL330. NO TCASII WARNING RECEIVED.